Heated hair roller

ABSTRACT

Heated hair roller comprises reservoir for liquefied gas, a member through which said gas diffuses and expands, and a duct for directing gas from said member against a catalyst.

United States Patent 1191 Morane et al.

HEATED HAIR ROLLER Inventors: Bruno P. Morane; Pierre Alexandre.

both of Paris. France Assignee'. LOreal. Paris. France Filed: Aug. 30. 1973 Appl. N03 393.082

Foreign Application Priority Data Sept. 15. 1972 France 72.32753 US. Cl. 132/33; 132/33 R Int. Cl. A450 2/12 Field 01 Search 132/33 R. 40. 42. 9;

(451 Oct. 21, 1975 [56] References Cited UNITED STATES PATENTS 3.257.541 6/1966 Jorgcnscn 132/33 R 3.563.251 2/1971 Jorgensen 132/33 R 3.614.381 10/1971 Popcil 132/33 R 3.693.636 9/1972 Tumlutl 132/33 11 Primary Examiner-O. E. McNeil! Attorney. Agent. or Firm-Brisebois & Kruger [57] ABSTRACT Heated hair roller comprises reservoir for liquefied gas. a member through which said gas diffuses and expands. and a duct for directing gas from said member against a catalyst.

20 Clalms. 5 Drawing Figures U.S. Patent Oct.21, 1975 4 Sheet 1 Ora 3,913,592

US. Patent Oct.21, 1975 Sheet2of3 3,913,592

FIG .2

US. Patent Oct. 21, 1975 Sheet3of3 3,913,592

FIGS

HEATED HAIR ROLLER SUMMARY OF THE lNVENTlON in a conventional hair curling process it is customary to wind the damp hair up on rollers and subject them to a certain amount of heat in order to dry the wound up hair and render the waves more permanent. in French Pat. No. 1,484.48 l a heating roller is described which comprises a catalyst designed to catalyze the oxidation of a combustible material in the gaseous phase. The combustible material is stored in liquid form in the roller inside a reservoir provided with an expansion valve. The combustible material may advantageously be a hydro-carbon having a low boiling point, such as butane.

in order to manufacture the heating roller above described in practical form French Pat. No. 70-29672 proposes an expansion valve for the combustible material comprising an outlet of very small diameter formed, for instance, by a laser beam.

it has been found that when such a device is placed in use relatively unsatisfactory results are obtained. in effect, it is necessary that the jet of combustible gas which escapes from the outlet be substantially constant and that it reach the catalyst in the curler in such a manner as to cause combustion, which takes place on contact with the catalyst. However, with too small an outlet, that is to say one about microns in diameter, for example, the microparticles which may be found in the outlet orifice are capable of diverting the jet of combustible gas, which results in an instability in the combustion at the catalyst.

it is the object of the present invention to provide a heating roller of the type described in the French 'Pat. No. l,484,48l, which roller avoids the aforesaid disadvantages and does not comprise an outlet of such small diameter for distribution of the combustible gas. Applicant has resolved in another manner the two problems with which he was simultaneously confronted, to wit on the one hand the regulation of the fiow ofthe combustible gas from the reservoir and, on the other hand the directional guidance of the jet of combustible gas against the catalyst.

The present invention is therefore directed to a new article of manufacture which consists ofa heating roller comprising a substantially cylindrical hollow body defining a cylindrical volume which holds both a reservoir for liquefied combustible material under pressure equipped with an expansion valve and a catalyst intended to catalyze upon contact the combustion of the combustible material coming from said reservoir, said catalyst being in contact with the ambient air inside the roller. This roller is characterized by the fact that there is interposed between the reservoir and the catalyst a member which permits a small. substantially constant flow of combustible gas to pass therethrough when subjected to the pressure which prevails in the reservoir. at the end of said member. a rigid duet which collects the output of combustible gas obtained from said member and directs it towards a point in the central zone of the catalyst.

in a first embodiment of the inventin the member which permits a small flow of gas to pass therethrough consists ofa membrane which is permeable to the combustible gas. This membrane may advantageously conslst of a silicone product and. in particular. dlmethyisllane. The silicone membrane has a thickness between 40 and microns. preferably about 60 microns.

in this first embodiment of the invention it has been found that the gas flow through the membranes commercially available is often a little too small to easily heat the roller to a temperature approximating the desired temperature, that is to say one between 50 and C. This has led to an increase in the dimensions of the membrance which constitutes a disadvantage when it is desired to use rollers of small diameter.

in order to overcome this difficuity a second embodiment has been suggested in which the member through which the small flow of gas passes consists of a tablet of porous material such as may be obtained by agglomerating pulverulent products. Among the porous tablets which are particularly valuable are those obtained by compacting a calcium silicate powder, a steatite powder and a graphite powder.

in this second embodiment the gas flow through the tablet may be regulated by adjusting the pressure drop which takes place during the course of the passage through the tablet by adjusting the thickness of the tablet or the pressure at which the pulverulent material is compacted or sintered, and the granulometry of the pulverulent material selected.

The duct which, in accordance with the invention,

directs the gas flow through the member which may be traversed by a small gas flow is not a duct having a small diameter such as the outlet envisaged in French Pat. No. 70-29672. However, the selection of the diameter of this duct is not a matter of random choice, since for a given gas flow the larger the inner diameter of the duct, the lower the speed of ejection of the combustible gas. For one thing, it is necessary, in order to obtain good combustion, for the gas which arrives at the catalyst to constitute a mixture of 8-l2% of a combustible gas such as butane, in air. it has been found that if the speed of ejection of the combustible gas is kept low, the air which surrounds the initial jet of combustible gas so mixes with the gas that the desirable proportion between the combustible gas and air is more rapidly obtained, and this makes it necessary to bring the catalyst and the opening of the duct fairly close together. However, since the catalyst is heated by this combustion to a high temperature, for example, of the order of 700C, conduction along the duct, as well as radiation, causes a heating of the reservoir for the combustible material which creates the risk of explosion. Moreover, if the inner diameter of the duct is too small, the cost of manufacture of the duct is considerably increased, as well as the risk that it may become stopped up. The practice of the invention therefore involves the adoption of a compromise.

it is a further object of the present invention to provide a heated roller of the above defined type characterized by the fact that the inner diameter of the duct is between 0.l and 0.8 millimeters, and preferably about 0.4 millimeters.

in a preferred embodiment of the invention the catalyst consists of a tablet, the distance between the end of the duct and the median plane of the catalyst tablet lies between i and 4 millimeters. The duct consists of a section of a hypodermic needle made of stainless steel. The catalyst tablet is supported by a bracket having several arms, one end of each arm supporting the tablet while the other end is connected to a collar attached to the outer wall of the duct. The collar of the bracket is crimped to the duct.

it should be noted that the fact that the catalyst tablet is supported by a bracket fixed to the duct itself makes it possible. on the one hand. to locate the catalyst tablet with respect to the end of the duct. and on the other hand. to avoid any connecting support between the catalyst tablet and the wall of the roller. This latter point is important because the use of a connecting support would permit the transmission of localized heat to a zone of the wall of the roller which. on the one hand. might damage the wall in the overheated zone and. on the other hand. involves the risk of producing a zone of excessive heat for the hair wound on the roller.

in order to allow for the risk of transmission of heat in the direction of the reservoir. a risk which exists because of the proximity of the end of the duct to the cataiyst. the duct has been spaced or insulated from the combustible material reservoir.

it is accordingly the object of the present invention to provide a roller of the above type characterized by the fact that between the member traversed by a small gas flow and the duct through which said gas flow is evacuated an additional member is interposed. This additiional member is preferably made of an elastomeric material and its base is mounted on the member traversed by the gas while its summit carries the end of the duct.

in a first variation the aforesaid additional member is a nipple made of a rubbery material which is attached along its edge to the entire periphery of the member traversed by a small gas flow. The latter member is itself attached to the edges of the outlet of the reservoir holding the combustible material and crimping is used to seal together the nipple member and reservoir.

in a second embodiment the additional member between the member traversed by a small gas flow and the duct is a rubbery body comprising axial grooves, one end of which receives the member traversed by a small gas flow and the other end of which receives the terminal portion of the duct through which the gas flow is evacuated.

it should be noted that use of a device such as the one which has been described leads to two simultaneous advantages. in the first place the duct transversed by the gas flow is supported and in the second place a heat shield is provided between the zone of the roller where the combustion takes place and the reservoir for combustible material.

in order to initiate combustion on the catalyst when the flow of combustible gas begins to travel through the .duct it is convenient to provide priming means. for example a hot point. it has already been proposed in French Pat. No. 70-29672 to provide an electrical resistance in the neighborhood of the catalyst and simultaneously fill the gaseous combustible reservoir and temporarily supply the electrical resistance so as to create a point sufficiently hot to insure the beginning of combustion. lthas.however.been foundthatthe permanent maintenance of the electric resistance nearthe zone of combustion results in a rapid deterioration of this resistance. which becomes fragile and is rapidly broken. in orderiO avoid this disadvantage it is proposed. in accordance with the present invention. to create the hot point on the catalyst tablet by utilizing either an optical system having a short focal length. which by concentralion of light rays permits the creation of the desired temperature at a point on the catalyst tablet. or an electrical discharge system such as a piezo-electric system.forexample. which at the moment of the emission of the spark also makes it possible to obtain the desired result.

it is. however. necessary to exactly position the optical or piezo-electric lighters with respect to the catalyst tablet so that the point of concentration of the light rays or the spark discharged directs the energy exactly onto the catalyst tablet and not at a certain distance therefrom.

it is therefore the object of the present invention to provide a heating roller of the type described characterlzed by the fact that. in the axial zone of the roller on the side remote from the reservoir of combustible gas. there are supports on which. at the moment combustion is initiated one may rest an abutment surface of a device for delivering concentrated energy at a particular point.

in a preferred embodiment the device for delivering concentrated energy is an optical concentrator having a short focal length. in an alternative the device for delivering a concentrated energy is a piezo-electric device which makes it possible to produce a spark at each pressure exerted on the device. said spark supplying to the catalyst an energy preferably between i and 3 millijoules. The supports provided in the axial zone of the roller are radially positioned vanes shaped to conform to the abutment surface of the generator of concentrated energy.

in order to readily control the temperatures obtained on the surface of the roller it has been proposed in accordance with the invention to incorporate into the material of the roller temperature sensitive products which change color near the temperature which is desired for the surface of the roller. Moreover. since the rollers according to the invention cannot. like conventional rollers be pierced by pins for attaching the hair to the roller when the hair has been wound thereon. it has been suggested that the hair be held in place by a curved strip. the radius of curvature of the strip being less than half the outer diameter of the roller. A heat insulating layer may advantageously be provided on the surface of the bent strip which is in contact with the hair.

in order that the invention may be better understood. three embodiments thereof will now be described. purely by way of example. with reference to the accompanying drawings. on which:

FIG. 1 is an axial sectional view through a roller according to the first embodiment of the invention;

FIG. 2 shows in axial section a second embodiment of the invention;

FIG. 3 shows in axial section a roller according to a third embodiment of the invention:

FIG. 4 shows a piezo-electric lighter for the roller; and

FIG. 5 shows an optical lighter.

Referring to the drawings. it will be seen that reference numeral 1 indicates a roller body consisting of a substantially cylindrical wall carrying peripheral protuberances 2 which are regularly spaced and decrease in height from the ends toward the central zone of the rolier. The protuberances 2 are substantially frustoconical and are distributed over each quarter of the periphery of the roller in flve parallel rows. The body of the roller 1 is pierced in its central zone by five holes -3 positioned on each of the median generatrices of the four zones occupied by the frusto-conical protuberances 2. The holes 3 permit ventilation of the internal volume defined by the lateral cylindrical wall of the roller.

At one end the wall I carries on its internal surface six vanes 4 which project into the internal cylindrical volume 5 defined by the roller. At the end of the roller rmote from the vanes 4 is a cap 6 on which the lateral wall of a cylindrical reservoir 7 is mounted. The cap 6 constitutes the bottom of the reservoir 7. In its central zone the cap is pierced by an orifice having a median shoulder 8. The cap 6 has perforations 60 about its periphery which assure supplemental ventilation around the reservoir 7, in addition to that which is provided by the holes 3.

in the recess is mounted the rubber body 9 of a conventional valve. which valve comprises an internal valve member 10 which is positioned on a seat inside the valve body 9. The valve body 9 is held in the cap 6 by the shoulder 8. The valve makes it possible to fill the reservoir 7 through the duct 11 which communicates with the seat of the valve member 10.

To the end of the reservoir 7 which is remote from the cap 6 is connected a duct 14 consisting of a section of a stainless steel hypodermic needle. The internal diameter of the duct 14 is 0.4 millimeters. The axis of the duct 14 is substantially the same as that of the cylindrical wall I of the roller. A cup is mounted inside the end of the duct 14 remote from the end 14a. The cup 15 comprises a collar 150 through which it is connected to the duct 14 and four tabs 151 which hold at their ends a tablet 16 4 millimeters in diameter and I millimeter thick consisting of a platinum foam. The median plane of the tablet I6 is perpendicular to the axis of the roller 1. The tablet 16 is positioned substantially in the median plane of the roller 1. The sealed reservoir 7 holds l.2 cubic centimeters of liquefied butane I7 and may be filled through the valve 9-10-11.

All the components which have been described above are common to all of the embodiments illustrated on FIGS. 1, 2 and 3. In the case of FIGS. I and 2 the duct 14 is attached to the reservoir by a nipple 13 made of a rubbery material, which nipple 13 has its peripheral edge 13a sealed by crimping ring 12 tothe corresponding end of the reservoir 7. The duct 14 is slightly recessed in the zone 14a in which it is connected to the inner wall of the nipple 13.

The approximate diameter of the cylindrical walls 1 of the rollers represented on FIGS. 1 and 2 is about l9.6 millimeters for the inner surface and 22 millimeters for the outer surface. The approximate length of the roller is 70 millimeters. The wall I is made ofa plastic material of the poly (4-Methyl-i'-pentene) type having a density of 0.83. The approximate height of the nipple 13 is 7 millimeters. The length of the duct 14 is 5 millimeters. The distance between the end of the duct 14 which is gripped by the cup 15 and the surface of the tablet I6 opposite thereto is 2 millimeters. The diameter of the holes 3 is l.8 millimeters.

Referring now more particularly to FIG. I it will b seen that the crimping ring 12 holds a membrane 18 between the neclt of the reservoir 7 and the peripheral edge 13a of the nipple 13. This membranes is positioned on a support in the form ofa ring 18a, a sealing consists of dimethylsilane of the type sold by the Societe Rhone-Poulene under the trademark ROU 3928. The support 18a permits the gaseous butane to pass freely therethrough after it has traversed the membrane 18. For the active surface of a membrane having a diameter of about l0 millimeters the gaseous flow is about 350 cubic centimeters per hour. It is preferable to shape the inner wall of the nipple 13 to increase to the extent possible the active surface of the membrane 18.

In the embodiment shown on FIG. 2 it will be seen that the crimping ring 12 grips between the peripheral edge 13a of the nipple 13 and the neck of the reservoir 7 the edge 20a of a diffuser 20 comprising a tablet 21 formed of a calcium silicate powder agglomerated by compression. The tablet 21 is positioned in the member 20 opposite the orifice 20!: which opens into the internal chamber defined by the nipple 13. The grains of calcium silicate powder used have a diameter of about 50 microns. The sintering pressure utilized is 350 bars. The tablet 21 consists of a cylinder i$.4 millimeters in diameter and l millimeter thick. This results in a gaseous flow of 600 cubic centimeters per hour when the reservoir 7 is full of liquefied butane.

With the roller illustrated in FIG. I the temperature attained on the protuberances 2 after lighting is substantially constant after about 8 minutes and near 70C for an ambient temperature of 25C. This temperature is maintained for about minutes.

With a roller according to FIG. 2, the temperature 01 the frusto-conical protuberances 2 after a starting delay of 7 minutes is substantially constant at about C. This temperature is maintained for 30 minutes. in the case of these two rollers heated in their central zone the temperature gradient between the central zone and each end is at a maximum 10C per centimeter.

Referring now more particularly to FIG. 3. it will be seen that the reservoir 7, the case of which is closed by the cap 6 and the valve 9-10-11 comprises at its uppei part an annular collar 70 which defines a central reces: in which is positioned a substantially frusto-conica rubber body 22, which comprises a neck 23 into whici the annular collar 7a of the reservoir projects. The body 22 has a central axial bore 24. A cylinder 25 i: force-fitted into the lower part of the bore 24. This cyl inder consists of calcium silicate powder agglomerate by compression. The powder used and the sintering carried out have the same characteristics as set forth ir connection with FIG. 2. The cylinder 25 has a diamete of about 3 millimeters and a thickness of about 5 milli meters. The terminal portion of the duct 14 is force fitted into the other end of the bore 24. This produce a gas flow of 400 cubic centimeters per hour, when thr reservoir 7 is filled with liquefied butane. With the rol ler corresponding to FIG. 3 the results obtained an substantially identical to those indicated in connectioi with the roller of FIG. 2.

The operation of the rollers which has just been de scribed is as follows. The reservoir 7 is filled througi the valve 9-10-11 by introducing thereinto a predeter mined quantity of liquefied butane. Under the vapo tension of the butane it diffuses through the membran 18, or the tablet 21, or the cylinder 25. This results i a substantial loss in pressure so that when it reaches th other side of the diffuser member the butane has ex panded to the gaseous state. The flow of gaseous bu tane passes through the duct 14 and is conducted to th tablet 16, which constitutes a combustion catalyst.-'lhe jet of combustible gas between the end of the duct 14 and the tablet 16 is mixed with ambient air and the mixture which arrives at the tablet comprises about butane. A hot point is then created on the tablet 16 to initiate combustion.- For this-purpose there is introduced between the vanes 4 of the roller the end of a piczo-electric lighter adapted to produce a spark between two electrodes.

The piezoelectric lighter is provided with a supporting surface mating with the shape of the vanes4 so that these electrodes may be perfectly positioned with respect to the tablet 16. The said lighter (shown on FIG. 4) consists of a conventional spring blessed striker striking arm 28 the piezoelectric quartz crystal 30 when the roller 1 is pressed down against the collar 29 attached to that arm. This results in the discharge of an energy of 1.5 miilijouies between the electrodes 31 and 32, and in this case, forms a point on the tablet 16 which is sufficiently hot to initiate combustion. In an alternative form of the invention the piezo-electric device shown in FIG. 5 and which has just been described may be replaced by an optical device comprising a light 33 and a short focal length optical system such as the lens 34. in this case. the optical device is positioned by the vanes 4 so that the focal point at which light energy is concentrated is exactly in the center of the tablet 16. The current to the lamp 33 may be controlled by a siwtch 35.

When combustion has started it continues in a regular manner until the reservoir 7 is empty. The roller is internally ventilated by the orifices 6a and 3 and by the open end of the roller which is provided with the vanes 4. The heat released during combustion distributes itself through the entire roller without forming any hot point on the surface of the roller. it will. however, be appreciated that there exists a slight temperature gradient between the center and the end of the roller as previously indicated. it goes without saying that the embodiments which have just been described have been given purely by way of illustration and example and may be modified as to detail without thereby departing from the basic principles of the invention as defined by the following claims.

what is claimed is:

l. in a heating roller comprising a substantially cylindrical hollow body carrying therewithin a reservoir for holding under pressure a combustible material which is liquefied under said pressure, and a catalyst which sustains combustion of said material when contacted thereby, said catalyst being in contact withthe ambient air inside the roller and freely accessible from outside said roller. the improvement which comprises a member positioned between the reservoir and the catalyst through which said material gradually diffuses and expands under the pressure within the reservoir to provide a small substantially constant flow of combustible dimethyl siiane.

4. Roller as claimed in claim 2 in which the membrane'has a thickness between 40 and 80 microns.

5. Roller as claimed in claim 1 in which said member is a porous tablet ofagglomerated puiveruient material.

6. Roller according to claim 5 in which said puiverulent material is selected from the group consisting of calcium silicate. steatlte and graphite powders.

7. Roller as claimed in claim I in which the diameter of the duct is between 0.l and 0.8 millimeters.

8. Roller as claimed in claim 1 in which the catalyst consists of a tablet made of platinum chrome.

9. Roller as claimed in claim 7 in which the distance between the end of the duct and the median plane of the catalyst tablet is between i and 4 millimeters.

10. Roller as claimed in claim 7 in which the duct comprises a segment of a stainless steel hypodermic needle.

11. Roller as claimed in claim 8 in which the catalyst tablet is supported by a bracket having several arms, with one end of each arm supporting the tablet while the other'end of each arm is connected to a collar attached to the outer wall of the duct.

12. Roller as claimed in claim 1 comprising an elastomeric connector between said member and duct, one end of which connector is attached to said member and the other end of which is connected to said duct.

[3. Roller according to claim 12 in which said connector is a nipple made of a rubbery material and the edge of the end of said nipple attached to said member is attached to the entire periphery of said member, said member being itself attached to the peripheral edge of the outlet of the reservoir enclosing the combustible material.

1. Roller according to claim 12 in which the connector between said member and duct is a rubbery body comprising an axial passage, one end of which receives said member and the other end of which receives one end of said duct. and the rubbery body blocks an orifice in the upper end of the reservoir.

1!. Roller according to claim 1 comprising locating members at one end of said roller for supporting and locating an ignition device when combustion is to be initiated.

l6. Roller as claimed in claim 15 in which the ignition device is an optical concentrator having a short focal length.

17. Roller as claimed in claim 15 in which the ignition device is a piezo-electric device which produces, when pressure is applied thereto. a spark capable of applying to said catalyst an energy between 1 and 3 millijoules.

l8. Roller as claimed in claim 15 in which the locating members in the end of the roller are radial fins gas, said member defining at least part of one wall of a chamber on the side of said member remote from said reservoir, and an elongated longitudinally unobstructed duct between said catalyst and chamber having an inlet opening directly into said chamber and an outlet. ssld duct and chamber being substantially sealed against said ambient air except at said outlet. whereby said duct receives a flow consisting essentially of combustible gas from said member. and said duct being posidiameter of the roller.

shaped to mate with corresponding surfaces on the ignition device.

19. Roller as claimed in claim 1 which comprises a heat sensitive material which changes color at about the temperature which is desired for the surface of the roller.

- 20. In combination. a roller as claimed in claim l and an arcuate clip having a diameter less than the external i i i i 

1. In a heating roller comprising a substantially cylindrical hollow body carrying therewithin a reservoir for holding under pressure a combustible material which is liquefied under said pressure, and a catalyst which sustains combustion of said material when contacted thereby, said catalyst being in contact with the ambient air inside the roller and freely accessible from outside said roller, the improvement which comprises a member positioned between the reservoir and the catalyst through which said material gradually diffuses and expands under the pressure within the reservoir to provide a small substantially constant flow of combustible gas, said member defining at least part of one wall of a chamber on the side of said member remote from said reservoir, and an elongated longitudinally unobstructed duct between said catalyst and chamber having an inlet opening directly into said chamber and an outlet, said duct and chamber being substantially sealed against said ambient air except at said outlet, whereby said duct receives a flow consisting essentially of combustible gas from said member, and said duct being positioned to direct said flow through said ambient air against the center of said catalyst.
 2. Roller according to claim 1 in which said member is a membrane which is permeable to the combustible gas.
 3. Roller as claimed in claim 2 in which the permeable membrane is made of a silicone and in particular dimethyl silane.
 4. Roller as claimed in claim 2 in which the membrane has a thickness between 40 and 80 microns.
 5. Roller as claimed in claim 1 in which said member is a porous tablet of agglomerated pulverulent material.
 6. Roller according to claim 5 in which said pulverulent material is selected from the group consisting of calcium silicate, steatite and graphite powders.
 7. Roller as claimed in claim 1 in which the diameter of the duct is between 0.1 and 0.8 millimeters.
 8. Roller as claimed in claim 1 in which the catalyst consists of a tablet made of platinum chrome.
 9. Roller as claimed in claim 7 in which the distance between the end of the duct and the median plane of the catalyst tablet is between 1 and 4 millimeters.
 10. Roller as claimed in claim 7 in which the duct comprises a segment of a stainless steel hypodermic needle.
 11. Roller as claimed in claim 8 in which the catalyst tablet is supported by a bracket having several arms, with one end of each arm supporting the tablet while the other end of each arm is connected to a collar attached to the outer wall of the duct.
 12. Roller as claimed in claim 1 comprising an elastomeric connector between said member and duct, one end of which connector is attached to said member and the other end of which is connected to said duct.
 13. Roller according to claim 12 in which said connector is a nipple made of a rubbery material and the edge of the end of said nipple attached to said member is attached to the entire periphery of said member, said member being itself attached to the peripheral edge of the outlet of the reservoir enclosing the combustible material.
 14. Roller according to claim 12 in which the connector between said member and duct is a rubbery body comprising an axial passage, one end of which receives said member and the other end of which receives one end of said duct, and the rubbery body blocks an orifice in the upper end of the reservoir.
 15. Roller according to claim 1 comprising locating members at one end of said roller for supporting and locating an ignition device when combustion is to be initiated.
 16. Roller as claimed in claim 15 in which the ignition device is an optical concentrator having a short focal length.
 17. Roller as claimed in claim 15 in which the ignition device is a piezo-electric device which produces, when pressure is applied thereto, a spark capable of applying to said catalyst an energy between 1 and 3 millijoules.
 18. Roller as claimed in claim 15 in which the locating members in the end of the roller are radial fins shaped to mate with corresponding surfaces on the ignition device.
 19. Roller as claimed in claim 1 which comprises a heat sensitive material which changes color at about the temperature which is desired for the surface of the roller.
 20. In combination, a roller as claimed in claim 1 and an arcuate clip having a diameter less than the external diameter of the roller. 